The present disclosure relates to lawful interception (LI) and security issues for proximity services (ProSe) such as D2D communications in the licensed spectrum, i.e. over the air interface of a wireless communication system.
Presently, the LI functionality is located in the core network. However, ProSe is promoting the (at least partly network-controlled) discovery and communication between UEs that are in proximity to each other to be able to use a “direct mode” or “locally-routed” path, which may not involve the core network. Namely, the direct mode path is a direct connection between the two UEs without involving further network elements such as an eNB. The locally-routed path is an indirect connection between the two UEs via an eNB without involving the core network.
Thus, the connection of UEs by proximity service does not involve the core network. Therefore, the LI functionality may not be applicable to ProSe connections and/or any intercepted information may not be available to the core network LI entities.
Accordingly, ProSe connections such as direct D2D communications in the licensed spectrum pose many challenges for the implementation of the required lawful interception (LI) and further desirable security features. Even in network-controlled direct D2D communications, as the user data is exchanged between the devices directly over the air interface and is not routed via any infrastructure network element, monitoring the content of communications is not readily possible with the present LI functionality in the core network. Further, even though the network may control the initial setup and resource allocation of direct D2D communications, it is not readily possible with the present LI functionality in the core network to take full control of the set up and allocated D2D connection, e.g. taking back allocated resources or releasing the D2D connection from misbehaving devices which hold on to the existing D2D connection and misuse it.
One option was discussed in the document “LS on Proximity Services and Lawful Interception from SA3-LI to SA1,2,3” (SA3LI13_033r1, 3GPP TSG-SA3-LI Meeting #48, Dublin, Ireland, 5-7 Feb. 2013) and the document “Solution for direct discovery and communication using E-UTRAN” (S2-130308, SA WG2 Meeting #95, Prague, Czech Republic, 28 Jan.-1 Feb. 2013) to disable ProSe capabilities for UEs under surveillance or move the communication for the UE under surveillance from ProSe communication mode to infrastructure mode. That is, the ProSe communication is disabled for these UEs so that the communication is performed via the core network, so that the LI functionality in the core network is enabled. However, as indicated in the document “LS on Proximity Services and Lawful Interception from SA3-LI to SA1,2,3” mentioned above, detectability issues need to be considered for this option, as LI should be done in a non-detectable manner. In addition, moving ProSe communication to infrastructure mode may degrade the communication performance (e.g. delay and perhaps also throughput), which may not be favorable by the end user and this also means the benefits of ProSe communication may not be achieved as EPC, e.g. P-GW or S-GW is involved in the ProSe communication user plane data transportation.
Thus, there is a need to facilitate lawful interception and security in a case in which devices, including at least one device to be intercepted, use proximity service connections (such as e.g. direct D2D communications over the air interface without routing via any infrastructure network element). In particular, it is desirable to facilitate lawful interception and security based admission control in such case of proximity service connections.